Low-Cost, High-Performance Hybrid Membranes for Redox Flow Batteries

The ion exchange membrane is the key component in redox flow batteries (RFBs) as it critically determines the RFB performance and its economic viability. The membrane should possess the following properties to ensure high energy efficiency and long cycle life of RFBs: high proton conductivity, low permeability of active redox species, and high chemical stability. In addition, low cost and high durability are also necessary requirements of the membrane before broad market penetration of RFBs can be achieved. At present, commercial membranes cannot satisfy all of the above requirements. This SBIR project aims to develop low-cost, high performance hybrid PEMs for RFBs by an intricate hybrid scheme in a polymer-polymer-inorganic system. Such membranes shall have high chemical stability in RFB electrolytes, high proton conductivity, low permeability of vanadium ions, along with high dimensional stability, high mechanical strength and durability, and lower cost than Nafion membranes. In Phase I, composition-processing-microstructure-property relations of the novel hybrid membrane will be established through detailed characterization, and performance of the membrane for vanadium RFBs will be evaluated. Commercial applications and other benefits: Redox flow battery (RFB) is one of potential technologies for stationary electrical energy storage. The feature of decoupling between the energy and power, and the extremely large capacities possible from RFBs make them well suited to use in large power storage and high output applications such as for transmission grid operations, in helping to average out the production of highly variable generation sources such as wind or solar power. Their extremely rapid response times also make them well suited to UPS type applications